1. Field of the Invention
This invention relates to a rotation preventing structure for limiting the rotation of a movable connector (hereinafter referred to as "a movable-connector rotation preventing structure", when applicable).
2. Description of Relevant Art
A variety of electrical devices are mounted on vehicles, such as automobiles, which require the supply of electric power. For instance, an interior lamp is generally mounted as shown in FIG. 5. That is, a vehicle-body-side connector 3 connected to an electrical wire 1 is mounted on a roof board 5, while the lamp 9 has a lamp-side connector 7 to be engaged with the vehicle-body-side connector 3. Hence, simultaneously to when the lamp 9 is installed, the lamp-side connector 7 is electrically connected to the vehicle-body-side connector 3. With the above-described structure, in engaging the two connectors 3 and 7 to each other, it is necessary to move the vehicle-body side connector 3 so as to be aligned with the position of the lamp-side connector 7.
Hence, a so-called "movable connector" has been proposed in the art which is movable to overcome the relative positional shift of the two connectors during the installation of the lamp. As shown in FIG. 6, the movable connector has four elastic locking pieces 13, provided respectively on four sides of a rectangular-box-shaped connector housing. The elastic locking pieces 13 have locking protrusions 13a at the outer ends thereof, respectively. The locking protrusions 13a are locked to the edge of a rectangular mounting hole 15, to mount the movable connector on the roof board 5.
As is apparent from the above description, the movable connector 11 is secured to the mounting hole 15 with the aid of the elastic locking pieces 13. Hence, the elastic deformation of the elastic locking pieces 13 allows the movable connector 11 to slightly rotate, thus correcting any positional shift of the movable connector with respect to the mating connector (not shown).
In the case of the above-described movable connector 11, the four locking protrusions 13a are locked to the four edges of the rectangular mounting hole 15 by the elastic forces of the four elastic locking pieces provided on the four sides of the connector housing. Hence, when an external force acts on the movable connector 11 to turn the latter about the inserting central axis c of the connector 11, the pairs of elastic locking pieces 13 which are confronted with each other are bent inwardly (towards each other), so that the movable connector 11 is turned with ease. If the movable connector 11 is turned excessively in this manner, then it is difficult to correct the positional shift of the movable connector with respect to the mating connector, and it is impossible to engage the two connectors with each other.
On the other hand, a movable connector 23 as shown in FIG. 8 has been developed by the present inventors, in which the inserting central axis c of a locking section 19 is not the same as the fitting central axis e of a connector 21. If the locking section 19 is turned about the inserting central axis c, the connector 21 is moved circularly with the locking section 19 as the center, thus being greatly shifted. In this case, a difficulty is involved that, although the electrical device is mounted, the connector 21 is not fitted to the locking section 19.
If the locking section 19 is turned excessively, then the elastic locking pieces 13 are twisted, so that the locking pieces 13 and the connector 21 may be damaged.
In view of the foregoing, an object of the invention is to provide a rotation preventing structure for a movable connector which prevents the movable connector from being turned beyond a predetermined range of angles, to thereby enhance the function of correcting the positional shift of the movable connector, and to prevent the connector housing from damage.